This application relates to a new class of cationic lipids which can be used in lipid particles and in the formation of lipid-nucleic acid complexes for cell transfection.
Monovalent cationic lipids are known in the art, for example as described in U.S. Pat. Nos. 6,320,017; 5,976,567; 5,965,542 and 5,785,992, which are incorporated herein by reference. Plasmid DNA-cationic lipid complexes are the leading non-viral gene therapy vectors used in the clinical setting. (1–4). However, the levels of gene expression that can be achieved using these complexes are substantially lower than can be achieved using viral vectors. Considerable effort has therefore been devoted to synthesizing new cationic lipids that have improved transfection properties over those currently available. (5–10).